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# Copyright (C) 2008, One Laptop per Child
# Author: Sayamindu Dasgupta <sayamindu@laptop.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
import logging
import cairo
import math
from gi.repository import Gtk
from gi.repository import Gdk
from gi.repository import GdkPixbuf
from gi.repository import GObject
ZOOM_STEP = 0.05
ZOOM_MAX = 4
ZOOM_MIN = 0.05
def _surface_from_file(file_location, ctx):
pixbuf = GdkPixbuf.Pixbuf.new_from_file(file_location)
surface = ctx.get_target().create_similar(
cairo.CONTENT_COLOR_ALPHA, pixbuf.get_width(),
pixbuf.get_height())
ctx_surface = cairo.Context(surface)
Gdk.cairo_set_source_pixbuf(ctx_surface, pixbuf, 0, 0)
ctx_surface.paint()
return surface
def _rotate_surface(surface, direction):
ctx = cairo.Context(surface)
new_surface = ctx.get_target().create_similar(
cairo.CONTENT_COLOR_ALPHA, surface.get_height(),
surface.get_width())
ctx_surface = cairo.Context(new_surface)
if direction == 1:
ctx_surface.translate(surface.get_height(), 0)
else:
ctx_surface.translate(0, surface.get_width())
ctx_surface.rotate(math.pi / 2 * direction)
ctx_surface.set_source_surface(surface, 0, 0)
ctx_surface.paint()
return new_surface
class ImageViewer(Gtk.DrawingArea):
def __init__(self):
Gtk.DrawingArea.__init__(self)
self._file_location = None
self._surface = None
self._zoom = None
self._target_point = None
self._anchor_point = None
self._zoomtouch_scale = 1
self.connect('draw', self.__draw_cb)
def set_file_location(self, file_location):
self._file_location = file_location
self.queue_draw()
def _center_target_point(self):
alloc = self.get_allocation()
self._target_point = (alloc.width / 2, alloc.height / 2)
def _center_anchor_point(self):
self._anchor_point = (self._surface.get_width() / 2,
self._surface.get_height() / 2)
def set_zoom(self, zoom):
if zoom < ZOOM_MIN or zoom > ZOOM_MAX:
return
self._zoom = zoom
self.queue_draw()
def get_zoom(self):
return self._zoom
def can_zoom_in(self):
return self._zoom + ZOOM_STEP < ZOOM_MAX
def can_zoom_out(self):
return self._zoom - ZOOM_STEP > ZOOM_MIN
def zoom_in(self):
if not self.can_zoom_in():
return
self._zoom += ZOOM_STEP
self.queue_draw()
def zoom_out(self):
if not self.can_zoom_out():
return
self._zoom -= ZOOM_MIN
self.queue_draw()
def zoom_to_fit(self):
# This tries to figure out a best fit model
# If the image can fit in, we show it in 1:1,
# in any other case we show it in a fit to screen way
alloc = self.get_allocation()
surface_width = self._surface.get_width()
surface_height = self._surface.get_height()
if alloc.width < surface_width or alloc.height < surface_height:
# Image is larger than allocated size
self._zoom = min(alloc.width * 1.0 / surface_width,
alloc.height * 1.0 / surface_height)
else:
self._zoom = 1.0
self._center_target_point()
self._center_anchor_point()
self.queue_draw()
def zoom_original(self):
self._zoom = 1
self.queue_draw()
def start_zoomtouch(self, center):
self._zoomtouch_scale = 1
prev_target_point = self._target_point
# Set target point to the relative coordinates of this view.
alloc = self.get_allocation()
self._target_point = (center[1] - alloc.x, center[2] - alloc.y)
# Calculate the new anchor point.
prev_anchor_scaled = (self._anchor_point[0] * self._zoom,
self._anchor_point[1] * self._zoom)
# This vector is the top left coordinate of the scaled image.
scaled_image_topleft = (prev_target_point[0] - prev_anchor_scaled[0],
prev_target_point[1] - prev_anchor_scaled[1])
anchor_scaled = (self._target_point[0] - scaled_image_topleft[0],
self._target_point[1] - scaled_image_topleft[1])
self._anchor_point = (int(anchor_scaled[0] * 1.0 / self._zoom),
int(anchor_scaled[1] * 1.0 / self._zoom))
self.queue_draw()
def update_zoomtouch(self, center, scale):
self._zoomtouch_scale = scale
# Set target point to the relative coordinates of this view.
alloc = self.get_allocation()
self._target_point = (center[1] - alloc.x, center[2] - alloc.y)
self.queue_draw()
def finish_zoomtouch(self):
# Apply zoom
self._zoom = self._zoom * self._zoomtouch_scale
self._zoomtouch_scale = 1
# Restrict zoom values
if self._zoom < ZOOM_MIN:
self._zoom = ZOOM_MIN
elif self._zoom > ZOOM_MAX:
self._zoom = ZOOM_MAX
# If at the current size the image surface is smaller than the
# available space, center it on the canvas.
alloc = self.get_allocation()
scaled_width = self._surface.get_width() * self._zoom
scaled_height = self._surface.get_height() * self._zoom
if alloc.width >= scaled_width and alloc.height >= scaled_height:
self._center_target_point()
self._center_anchor_point()
self.queue_draw()
def rotate_anticlockwise(self):
self._surface = _rotate_surface(self._surface, -1)
# Recalculate the anchor point to make it relative to the new
# top left corner.
self._anchor_point = (
self._anchor_point[1],
self._surface.get_height() - self._anchor_point[0])
self.queue_draw()
def rotate_clockwise(self):
self._surface = _rotate_surface(self._surface, 1)
# Recalculate the anchor point to make it relative to the new
# top left corner.
self._anchor_point = (
self._surface.get_width() - self._anchor_point[1],
self._anchor_point[0])
self.queue_draw()
def __draw_cb(self, widget, ctx):
# If the image surface is not set, it reads it from the file
# location. If the file location is not set yet, it just
# returns.
if self._surface is None:
if self._file_location is None:
return
self._surface = _surface_from_file(self._file_location, ctx)
if self._zoom is None:
self.zoom_to_fit()
# If no target point was set via pinch-to-zoom, default to the
# center of the screen.
if self._target_point is None:
self._center_target_point()
# If no anchor point was set via pinch-to-zoom, default to the
# center of the surface.
if self._anchor_point is None:
self._center_anchor_point()
# FIXME investigate
ctx.set_antialias(cairo.ANTIALIAS_NONE)
ctx.translate(*self._target_point)
zoom_absolute = self._zoom * self._zoomtouch_scale
ctx.scale(zoom_absolute, zoom_absolute)
ctx.translate(self._anchor_point[0] * -1, self._anchor_point[1] * -1)
ctx.set_source_surface(self._surface, 0, 0)
# FIXME investigate
ctx.get_source().set_filter(cairo.FILTER_NEAREST)
ctx.paint()
if __name__ == '__main__':
import sys
window = Gtk.Window()
window.connect("destroy", Gtk.main_quit)
view = ImageViewer()
view.set_file_location(sys.argv[1])
window.add(view)
view.show()
window.set_size_request(800, 600)
window.show()
Gtk.main()
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